26 



Plate. The figures on the plate represent as follows : Fig. I, ordinary form ; Fig. 

 2, f. compacta ; Fig. 3, a portion of a leaf X 5 Fi g- 4. mature oospore ; Fig. 5 

 fragments of the spore membrane, showing reticulations like faint depressions in the 

 surface, the surface in general being very indistinctly roughened. 



NITELLA PYGMAEA A. Br. A small plant (one or two inches long), 

 dark gray. 



The stems arise from one or two swollen leafless nodes, and produce, 

 at first, usually two spreading verticils, consisting of longish leaves ; 

 afterward there arises a series of several short- leaved, contracted verti- 

 cils. From the sterile and lower fertile whorls two (usually) unequal 

 branches arise, which produce similar "capitulae." A verticil bears 

 six leaves, equally twice divided, in fertile whorls partly thrice divided. 

 In the second node there is often an undivided ray (leaflet). In the 

 sterile leaves the first segment is twice as long as the second, the third 

 likewise longer than the succeeding, the second and third equal in 

 length. The terminal ray one-celled, except the mucro, which is 

 smaller than the preceding cell, similar to batrachosperma, to which it 

 is in its general appearance more similar than to tenuissima ; yet, in 

 spite of its minuteness, it is stouter than N. batrachospenna. Stem 480 

 to 500 in diam.; first segment of the leaf 360 to 380, second 260 to 

 280, third 180 to 200 (in the upper verticil 120 to 140). Mucro 60 to 

 70 long, 20 to scarcely 30 in diam. Antheridia and oogonia on the 

 first node only, aggregated (two to three, usually two oogonia and one 

 antheridinm). Antheridia 240 to 250 in diam. Entire oogonium 340 

 to 360 long, 280 to 300 broad ; oospore yellowish brown, with 7 ridges, 

 250 long, 210 broad (larger than tenuissima and differing from batra- 

 chasforma by its ridges, not prominent). 



Figures (on plate, with minuta) and description, copied from Braun-Norstedt 

 Fragmenta ; specimens not seen. 



NITELLA MINUTA A. Characeae, Amer. Exsiccatae, No. 34. 



This is one of the most minute Nitellae, rivalling N. batrachospenna 

 A. Br. in smallness. Stem from 2 to 6 cm. in length, about 130 in diam. 

 The leaves of the sterile verticils spreading, very small, filiform. Leaves 

 of the fertile verticils condensed into small globular masses, enveloped 

 in jelly, long-overtopped by the sterile leaves. Fertile leaves twice 

 divided ; first segment 104 in diam., about 460 long; first node fertile, 

 bearing four rays; second segment 80 in diam., about 440 long; second 

 node fertile, bearing three terminals; terminals 30 in diam., about 800 

 long, terminating in a mucro which is 30 in diam. at base and about 

 120 long. Oogonia single at each node of the leaf; oospores 350 long, 

 285 broad with six thick and prominent ridges, its surface marked by 

 roundish elevations or granules. (See Fig. 5.) 



